It is known to use NAND flash memory in many types of read/write memory cards such as: a Multi Media Card (MMC), a Secure Digital (SD) card, a Compact Flash (CF) card, and a memory stick, etc. A conventional MMC typically communicates only with an MMC type host, and therefore, may require a separate Universal Serial Bus (USB) reader to communicate with a USB host. However, many problems arise when trying to add a USB function to a conventional MMC controller, such as how to provide the needed clocks for the USB interface.